BALSAMIC GLAZED CHICKEN AND PEACH PANZANELLA

1 large red onion, sliced into wedges • 2 Waitrose & Partners peaches, sliced into wedges • 8 British chicken thighs • 2 tbsp balsamic vinegar glaze • 300g pack cooked beetroot, drained and sliced into wedges • 2 tbsp olive oil • 250g sourdough bread (crusts on), torn into bite-sized chunks • 90g pack rocket